Ingore SSL_ERROR_WANT_READ/WRITE errors

Before this change, the connection would be defuncted when the error
occurred.  Instead, these can safely be ignored and the recv() call
retried.

CHANGELOG.rst

@@ -12,6 +12,9 @@ Bug Fixes
 * Correctly supply compaction and compression parameters in CREATE statements
   for tables when working with Cassandra 2.0+
 * Lowercase boolean literals when generating schemas
+* Ignore SSL_ERROR_WANT_READ and SSL_ERROR_WANT_WRITE socket errors.  Previously,
+  these resulted in the connection being defuncted, but they can safely be
+  ignored by the driver.
 
 Other
 -----

cassandra/io/asyncorereactor.py

@@ -258,7 +258,11 @@ class AsyncoreConnection(Connection, asyncore.dispatcher):
                 if len(buf) < self.in_buffer_size:
                     break
         except socket.error as err:
-            if err.args[0] not in NONBLOCKING:
+            if ssl and isinstance(err, ssl.SSLError):
+                if err.args[0] not in (ssl.SSL_ERROR_WANT_READ, ssl.SSL_ERROR_WANT_WRITE):
+                    self.defunct(err)
+                    return
+            elif err.args[0] not in NONBLOCKING:
                 self.defunct(err)
                 return
 

cassandra/io/libevreactor.py

@@ -311,7 +311,11 @@ class LibevConnection(Connection):
                 if len(buf) < self.in_buffer_size:
                     break
         except socket.error as err:
-            if err.args[0] not in NONBLOCKING:
+            if ssl and isinstance(err, ssl.SSLError):
+                if err.args[0] not in (ssl.SSL_ERROR_WANT_READ, ssl.SSL_ERROR_WANT_WRITE):
+                    self.defunct(err)
+                    return
+            elif err.args[0] not in NONBLOCKING:
                 self.defunct(err)
                 return